Leviticus 5:18

18 They are to bring to the priest as a guilt offering a ram from the flock, one without defect and of the proper value. In this way the priest will make atonement for them for the wrong they have committed unintentionally, and they will be forgiven.

Read Leviticus 5:18 Using Other Translations

And he shall bring a ram without blemish out of the flock, with thy estimation, for a trespass offering, unto the priest: and the priest shall make an atonement for him concerning his ignorance wherein he erred and wist it not, and it shall be forgiven him.
He shall bring to the priest a ram without blemish out of the flock, or its equivalent for a guilt offering, and the priest shall make atonement for him for the mistake that he made unintentionally, and he shall be forgiven.
For a guilt offering, you must bring to the priest your own ram with no defects, or you may buy one of equal value. Through this process the priest will purify you from your unintentional sin, making you right with the LORD, and you will be forgiven.